Telephone answering systems which may be remotely controlled are described in U.S. Pat. Nos. 3,757,049 and 3,903,369, both of which are assigned to the present assignee. A remotely controlled telephone answering system is also described in the copending application referred to above.
The telephone answering systems described in the patents, as well as the telephone answering system described in the copending application, each includes an announcement tape which is activated during an announcement interval (T.sub.1) in response to a telephone call, and which causes a recorded announcement on the announcement tape to be transmitted to the calling party over the telephone line during that interval. At the end of the announcement interval (T.sub.1), a message tape is activated, and it records the message from the calling party during an ensuing time interval (T.sub.2). The time interval (T.sub.2) may be of any predetermined length, or it may continue within the limits of the system, for as long as the calling party is talking (VOX).
The telephone answering systems described in the patents and in the copending application are capable of remote control, which enables the user to call up his machine over the telephone line and to activate the machine to cause it to transmit to him all the accumulated messages previously recorded on the message tape. This is achieved in the systems described in the patents and in the copending application by means of a small portable remote control unit which is held by the user up to the mouthpiece of the telephone, and which is pushbutton controlled to transmit a digitally coded signal including signal tones of predetermined frequencies, over the telephone line.
The present application is also concerned with such a remote control system, and, particularly, with a system which is constructed to incorporate a prompting feature, whereby the caller, merely by again sending the digital code over the telephone line, can cause the machine to repeat the last message, and which also can be used to cause the machine to erase all the previously recorded messages, after all the messages have been read successively to the calling party.